Ecology

By :- Gourav Trivedi
Ecology
• The word ecology emerged from two
Greek words: “Oikos” and “logos”.
“Oikos” means “house” or “estate,”
and “logos” means “study.”
• Its literal meaning is the study of
nature’s home or family.
• The term was coined by Ernst Haeckel
in 1866, however it was first introduced
by Hans Reiter in 1885.
• Ecology is “the scientific study of the
connection between living creatures
and their environment”.
• Ernst Haeckel (1866-
1870)explained about
ecology in the following way:
Ecology is a body of
knowledge concerning the
relations of organism, both to
its inorganic and to its
organic environment;
including friendly and
inimical relation with those
animals and plants with
which it comes in contact
with.
Subdivisions of Ecology

• Autecology
• Autecology is the study of particular
species or individuals in relation to
their environmental surroundings.
• Species-specific and population-
specific autecology are the two main
methods to autecological research
(a) species-specific autecology
examines individual species,
whereas population ecology analyses
individuals of the same species.
• Synecology
• It is the study of the community of
living organisms as an individual unit.
• Community ecology is focused on the
study of biotic (living) communities
composed of interdependent plants
and animals in a given region. A
community of living creatures and
their surroundings is considered a unit
of nature under ecosystem ecology.
• Habitat Ecology
• Habitat ecology involves ecological
study of organisms’ habitat or
environment and its influence on
them. Diverse habitats like terrestrial,
freshwater, marine and estuarine
habitats are studied.
 Levels of Organizations in Ecology

• Ecology encompasses the

study of individual,
organisms, population,
community, ecosystem,
biome and biosphere which
form the various levels of
ecological organisation.
Organism
• It is the lowest level of organization, which
includes both unicellular and multicellular
organisms.
• All the living species in this level exhibit all
the characteristics required for the existence
of life.
• The organism is an individual living being that
has the ability to act or function
independently. It may be a plant, animal,
bacterium, fungi, etc.
Population
• A population is a group of
individuals of a single species
living together within a particular
geographic area.
• They interbreed and compete with
each other for resources.
• A population is a group of
organisms usually of the same
species, occupying a defined area
during a specific time.
Community
• It refers to the several populations that interact
and inhabit a common environment and are
interdependent.
• In ecology, the term community, or more
appropriately ‘biotic community, refers to the
populations of different kinds of organisms
living together and sharing the same habitat.
• Members of a community also actively interact
with their environment. In a community, only
those plants and animals survive which are
adapted to a particular environment.
Types of Community
• On the basis of size and degree of relative independence
communities may be divided into two types:
• Major Community:
• These are large-sized, well organized and relatively
independent. They depend only on the sun’s energy from
outside and are independent of the inputs and outputs from
adjacent communities.
• Example: tropical evergreen forest in the North-East.
• Minor Communities:
• These are dependent on neighboring
communities and are often called
societies. They are secondary
aggregations within a major
community and are not therefore
completely independent units as far
as energy and nutrient dynamics are
concerned.
• Example: A mat of lichen on a cow
dung pad.
Ecosystem

• It is a set of all living species

and abiotic components
existing and interacting in a
given area.
• There is an interaction with
both living and nonliving
components of the
environment.
 Biosphere

• It is the highest level of

organization.
• It is the global ecological system
which consists of all the living
organisms and other factors
which support life.
• The biosphere mainly refers to
the part of the earth’s crust.
• The biosphere is a part of the
earth where life can exist.
• The biosphere is the biological component (supporting life) of
the earth which includes the lithosphere, hydrosphere and
atmosphere.
• The biosphere includes all living organisms on earth, together
with the dead organic matter produced by them.
• The biosphere is absent at extremes of the North and South
poles, the highest mountains and the deepest oceans since
existing hostile conditions there do not support life (life is the
characteristic feature of the biosphere).
• Occasionally spores of fungi and bacteria do occur at a great
height beyond 8,000 metres, but they are metabolically
inactive, and hence represent only dormant life.
• The biosphere represents a highly
integrated and interacting zone
comprising of the atmosphere (air),
hydrosphere (water) and
lithosphere (land).
• It is a narrow layer around the
surface of the earth. If we visualize
the earth to be the size of an apple
the biosphere would be as thick as
its skin.
Biome

• A biome is an area classified

according to the species that live in
that location.
• Temperature range, soil type, and
the amount of light and water are
unique to a particular place and
form the niches for specific species
allowing scientists to define the
biome.
Ecosystem
Ecosystem
• An ecosystem is a structural and functional
unit of ecology where the living organisms
interact with each other and the surrounding
environment.
• In other words, an ecosystem is a chain of
interactions between organisms and their
environment.
• The term “Ecosystem” was first coined by
A.G.Tansley, an English botanist, in 1935.
• An ecosystem can be visualised as a functional
unit of nature, where living organisms (producers,
consumers, and decomposers) interact among
themselves and also with the surrounding physical
environment.
• An ecosystem can be of any size but usually
encompasses specific and limited species. E.g.
Aquatic Ecosystem. (This is how ecosystem is
different from Environment)
• Everything that lives in an ecosystem is dependent
on the other species and elements that are also
part of that ecological community.
• If one part of an ecosystem is damaged or
disappears, it has an impact on everything else.
 Structure of the Ecosystem
• The structure of an ecosystem is
characterised by the organisation of both
biotic and abiotic components.
• This includes the distribution of energy in our
environment. It also includes the climatic
conditions prevailing in that particular
environment.
• The structure of an ecosystem can be split
into two main components, namely:
• Biotic Components
• Abiotic Components
Biotic Components
• Biotic components refer to all living components
in an ecosystem.
• Based on nutrition, biotic components can be
categorised into autotrophs, heterotrophs and
saprotrophs (or decomposers).
• Producers:-
• Producers include all autotrophs such as plants.
They are called autotrophs as they can produce
food through the process of photosynthesis.
• Consequently, all other organisms higher up on
the food chain rely on producers for food.
Consumers
• Consumers or heterotrophs are organisms that
depend on other organisms for food.
• Consumers are further classified into primary
consumers, secondary consumers and tertiary
consumers.
• Primary consumers:- Primary consumers are
always herbivores as they rely on producers for
food.
• Secondary consumers :- Secondary consumers
depend on primary consumers for energy. They
can either be carnivores or omnivores.
• Tertiary consumers:- Tertiary
consumers are organisms that
depend on secondary
consumers for food.
• Tertiary consumers can also be
carnivores or omnivores.
• Quaternary consumers :-
Quaternary consumers are
present in some food chains.
• These organisms prey on
tertiary consumers for energy.
• Furthermore, they are usually
at the top of a food chain as
they have no natural predators.
Decomposers

• Decomposers include
saprophytes such as fungi
and bacteria. They directly
thrive on the dead and
decaying organic matter.
• Decomposers are essential
for the ecosystem as they
help in recycling nutrients to
be reused by plants.
• Decomposers are the living component of the ecosystem that
breaks down waste material and dead organisms.
• Examples of decomposers include earthworms, dung beetles
and many species of fungi and bacteria.
• They feed on the decaying organic matter and convert this
matter into nitrogen and carbon dioxide.
• The saprophytes play a vital role in recycling the nutrients so
that the producers i.e. Plants can use them once again.
Abiotic Components
Abiotic Factors
• The term abiotic refers to all the non-living factors present in
an ecosystem. Sunlight, water and land, all constitute the
abiotic factors.
• Abiotic factors refer to all the non-living, i.e. Chemical and
physical factors present in the atmosphere, hydrosphere, and
lithosphere.
• Sunlight, air, precipitation, minerals, and soil are some
examples of abiotic factors.
• These factors have a significant impact on the survival and
reproduction of species in an ecosystem.
• For instance, without an adequate amount of sunlight,
autotrophic organisms may not be able to survive.
• When these organisms eventually die, it will create a shortage
of food for primary consumers.
• This effect cascades up the food chain, affecting every
organism.
• Consequently, it leads to an imbalance in the ecosystem.
• Examples of Abiotic Components:
• Water
• Light
• Temperature
• Humidity
• Soil
These abiotic factors fall into distinct
groups:
• PHYSICAL FACTORS:
• Temperature: Influences the metabolic processes of
organisms.
• Water (Rainfall): Availability of water crucial for survival.
• Light (Energy): Essential for photosynthesis in autotrophs.
• Soil: Composition affects plant growth and nutrient
availability.
• Atmospheric pressure: Affects breathing and physiological
processes in organisms.
• INORGANIC AND ORGANIC SUBSTANCES:
• Water: Vital for various biological processes.
• Oxygen: Essential for respiration in many organisms.
• Carbon: Fundamental for organic compounds.
• Nitrogen, Sulphur: Important elements for living organisms.
• Nitrates, Phosphates, and ions of various metals: Crucial for
plant nutrition.
Energy
• Energy from the sun is essential for maintenance of life. In the
case of plants, the sun directly supplies the necessary energy.
• Since animals cannot use solar energy directly they obtain it
indirectly by eating plants or animals or both.
• Energy determines the distribution of organisms in the
environment.
Rainfall
• Water is essential for all living beings. Majority of biochemical
reactions take place in an aqueous medium.
• Water helps to regulate body temperature.
• Further, water bodies form the habitat for many aquatic plants
and animals.
Temperature
• Temperature is a critical factor of the environment which
greatly influences survival of organisms.
• Organisms can tolerate only a certain range of temperature
and humidity.
Atmosphere
• The earth’s atmosphere is responsible for creating conditions
suitable for the existence of a healthy biosphere on this
planet.
Substratum
• Land is covered by soil and a wide variety of microbes,
protozoa, fungi and small animals (invertebrates) thrive in it.
• Roots of plants pierce through the soil to absorb water and
nutrients.
• Organisms can be terrestrial or aquatic. Terrestrial animals
live on land.
• Aquatic plants, animals and microbes live in fresh water as
well as in the sea.
Materials
• (i) Organic compound such as proteins, carbohydrates, lipids,
humic substances are formed from inorganic compound on
decomposition.
• (ii) Inorganic compound such as carbon dioxide, water,
sulphur, nitrates, phosphates, and ions of various metals are
essential for organisms to survive.
Types of
Ecosystem
 Types of Ecosystem

• Ecosystems are divided into

many types in ecology
according to the location or
the type of environment, such
as land or water. It can also
be categorized according to
how much energy an
Ecosystem uses.
• Aquatic Ecosystem
• Terrestrial Ecosystem
 Artificial Ecosystem:
• Artificial ecosystems, as the name
suggests, are environments that have been
intentionally created or modified by
humans.
• Artificial ecosystems are human-made
structures where biotic and abiotic
components are made to interact with
each other for survival.
• It is not self-sustaining and can perish
without human help. Examples of artificial
ecosystems include aquariums,
agriculture fields, zoos, etc.
• Human-made or Artificial
Ecosystem – When human beings
modify the already existing
ecosystem to meet their purpose
or create an ecosystem of their
own that mimics the natural
condition, those are called
artificial ecosystems
Natural Ecosystem
• A biological environment occurring freely in nature rather than
being created by man is called as a natural ecosystem
• A natural ecosystem is a community of living and non-living
entities and occurs freely in nature.
• Every component interacts together as a combined unit
through physical, chemical and biological processes.
• The discriminating factor of natural ecosystems from other
ecosystems is that they are completely natural.
• Their interactions in no way are influenced by human activity
as seen in the case of artificial ecosystems.
• Examples of natural
ecosystems are forests,
mountains, rivers, grasslands
etc
 Terrestrial Ecosystem

• A terrestrial ecosystem is a land-based

community of organisms and the
interactions of biotic and abiotic
components in a given area.
• Examples of terrestrial ecosystems
include the tundra, taigas, temperate
deciduous forests, tropical rainforests,
grasslands, and deserts.
Forest
ecosystem
• A forest ecosystem is a complex and
interconnected community of plants,
animals, microorganisms, and their
physical environment within a forested
area.
• They provide habitats for countless
organisms, from tiny insects to large
mammals, and support a diverse range
of flora.
• Temperature, humidity and soil are
essential elements for forest
ecosystem.
• Climate and soil nature determine
the distribution of vegetation.
• Forest ecosystem can be broadly
divided into three parts- tropical,
temperate and coniferous forests
which are found in low latitudes,
middle latitudes and high latitudes
respectively, but all these forest
patterns can be observed with the
increase in altitude even at the
same latitude.
Tropical forests

• The forests which are found

in the lower latitudes of the
earth, i.e. Between 30°N
latitude and 30°S latitude, are
called tropical forests.
• Tropical forests can be
divided into two parts:
• 1) Tropical evergreen forests
• 2) Tropical deciduous forests
Tropical evergreen • They are also called the lungs of the
earth.

forests • They are mainly found on both sides of

the equator.
• They are found in areas with year-round
rainfall and moderate climate where both
temperature and humidity are high.
• The average annual rainfall in these
forests is more than 200 cm.
• The leaves of these trees are large, many,
evergreen and thick. The trees have a high
canopy density.
• Due to lack of light reaching the ground,
the growth of vegetation on the ground is
very low.
• There is abundance of tall trees here (up to 60 m in height).
• There is abundance of tall trees here (up to 60 m in height).
Despite having high tree density, they are not of much
economic importance.
• The trees mainly found are hardwood trees like mahogany,
rubber, rosewood, sandalwood, ebony etc.
• Generally tree-dwelling and large animals reside here like
monkeys, langurs, elephants, giraffes, rhinoceros etc.
• These forests are distributed in Amazon Basin, Congo Basin,
Guinea Coast, Andaman and Nicobar Islands and North-
Eastern Australia etc.
Tropical Deciduous Forest
• These forests have a moderate climate with distinct seasons,
including a warm, dry summer.
• Annual rainfall ranges from 70–200 cm, and average summer
temperatures range from 27–32°C, with maximum
temperatures reaching 38–48°C in May and June.
• The trees in these forests are well adapted to seasonal
changes and often have deep roots that can access
groundwater during the dry season.
• They shed their leaves for about six to eight weeks during the
summer, and some common tree species include:
• They shed their leaves for about six to
eight weeks during the summer, and some
common tree species include:
• Kusum
• Bamboo
• Khair
• Sal
• Arjun
• Shisham
• Mulberry
• Sandalwood
• Tropical deciduous forests provide many important services to
the ecosystem, including:
• Habitat: They provide a home for many different species of
plants and animals.
• Timber: Hardwood trees like sal, teak, neem, and shisham are
used to make construction materials, furniture, and for
transportation.
• These species are overexploited for their high economic value
by humans. These forests are also cleared for carrying out
some agricultural activities.
• Tigers, lions, elephants, langurs, deer, bears, tortoises,
snakes, and monkeys are the common animals found in this
forest type.
• On the basis of precipitation and availability of water they are
further divided into two types
• Moist Deciduous Forests:
• Moist Deciduous Forests are found in the regions which receive
rainfall between 200-100cm annually.
• Mean annual temperature is around 24°C or 27°C and relative
humidity is around 60%-75% which favors this kind of vegetation.
• Dry Deciduous Forests:
• Dry Deciduous Forests are found in the areas receiving rainfall
between 70cm-100cm annually. Wet margin of the dry deciduous
forests merge into the moist deciduous forests and dry margins
merge into the thorn type vegetation.
• Tropical deciduous forests are found in drier areas north and south
of tropical rainforests, usually between 10° and 20° latitude. They
can be found in many parts of the world, including:
• South America: The Amazon, and the dry forests of the Pacific
Coast of northwest South America
• Mexico: Southern Mexico has some of the most diverse dry forests
in the world
• Southeast Asia: Myanmar
• India: Coastal regions of southwest India, and large parts of the
country
• Africa: Southwestern Africa
• Australia: Northern Australia
• Other: Sri Lanka, Bangladesh, and French Guiana
Temperate or mid-latitude forests

• These forests are found in the

middle latitudes i.e. Between 30
degrees north and south latitude
and 60 degrees north and south
latitude.
• These forests are mainly classified
into three parts-
• Mid-latitude evergreen forest or
temperate evergreen forest
• Mid-latitude evergreen forest
• Mediterranean forest
Mid-latitude evergreen forests
• These forests are found in the rain forests of the eastern
coastal areas of the continents in the subtropical regions.
• Broad-leaved trees like Lawrence, Mongolia, Eucalyptus, etc.
are found in these forests.
• These forests are spread in areas like South China, Japan,
South Brazil, South-eastern United States, etc.
Mid-latitude deciduous forests
• These are also called temperate tropical forests.
• Trees in these forests shed their leaves in winter.
• Summers are long and winters are short in these regions.
• The trees found in these forests have a predominance of
broad leaf trees.
• Mainly chestnut, maple, walnut etc. Trees are found here.
• These forests are spread in cold climate regions of North-
Eastern America, Southern Chile.
Mediterranean forests
• These forests are found in the western part of the continents in
the middle latitudes.
• Characterized by hot and dry summers and mild, wet winters.
• Here summers are hot while winters are cold and humid
because the year here is in winter.
• The main trees here are cork, olive, pine etc.
• This region is famous for juicy fruits like grapes, lemons,
oranges, pomegranates etc.
• This biome is also called chaparral.
• Mediterranean forests are known as the "Orchards of the World"
because of their fruit production.
• Citrus fruits like oranges, figs, olives, and grapes are commonly
grown in these forests.
• The plants of these forests have thick barks and waxy leaves to
reduce transpiration and adapt to dry summers.
• They are found in the western and southwestern margins of
continents, between 30° and 45° north and south of the equator.
• The Mediterranean Sea is the region with the most extensive
Mediterranean climate, which is named after the basin.
• Mediterranean forests are also found outside the Mediterranean
region in California, southwest Africa, southwest South America,
and southwest Australia
Taiga forests
• Taiga forests are a type of coniferous forest that are found
in the cold, subarctic regions of the Northern Hemisphere.
• They are also known as boreal forests or snow forests and
are the world’s largest land biome. Taiga forests are
characterized by:
• Trees
• Coniferous trees, which have needles instead of broad
leaves and never lose them. These trees include spruce,
pine, and fir.
• Taiga forests are found in Alaska, Canada, Scandinavia,
Siberia, and parts of northern Asia and Europe.
• The coniferous forest belts of Eurasia and
North America are the richest sources of
softwood.
• Softwood is used in building construction,
furniture, matches, paper and pulp, rayon
and other branches of the chemical industry.
• Conifers are conical in shape. Their conical
shape and sloping branches prevent snow
accumulation. It also offers little grip to the
winds.
• Transpiration can be quite rapid in the warm
summer. So, leaves are small, thick, leathery
and needle-shaped to check excessive
transpiration.
Grassland Ecosystem
• Grass refers to a wide variety of green, ground-covering non
woody plants that are short in stature.
• These plants belong to the plant family known as Poaceae.
• A grassland ecosystem is a biome characterized by vast
expanses of grasses, herbs, and occasionally some scattered
trees or shrubs.
• Grasslands are found on every continent except Antarctica
and can vary significantly in terms of climate, geography, and
species composition.
• UNESCO defines grassland as “land covered with herbaceous
plants with less than 10 percent tree and shrub cover” and
wooded grassland as 10-40 percent tree and shrub cover.
• Grassland ecosystems are water deficient ecosystems.
• These are lands which generally have open and continuous
and fairly flat areas of grasses.
• They are often located between temperate forests at high
latitudes and deserts at subtropical latitudes.
• Precipitation: The grasslands grow when annual rainfall ranges
from 25 to 75 cm, which is more than a true desert but not
enough to maintain a forest.
• Space cover: It makes about 20 to 40% of the world’s land
surface.
Types of Grassland
Ecosystem

• There are primarily two categories

of grasslands:-
• Tropical Grassland
• Temperate Grassland
• Tropical grasslands (Savanna): Tropical grassland is a type of
terrestrial biome characterized by a combination of grasses
and scattered trees or shrubs.
• These Grassland ecosystems are found in tropical regions with
distinct wet and dry seasons.
• Temperate grasslands (Steppes): Temperate grasslands are
terrestrial ecosystems characterized by vast expanses of
grasses with minimal tree cover.
• These grassland ecosystems are typically found in regions
with temperate climates that experience distinct seasons,
including hot summers and cold winters, present.
Tropical Grasslands
• Tropical grasslands have dry and wet seasons that remain warm all the time.
These regions are warm throughout the year, followed by dry and wet seasons.
Tropical Grasslands are the ones which receive 50 cm to 130 cm rain.
• Also, the tropical grasslands contain quite short plants which makes it an
excellent hunting ground. For instance, the African savanna is one of the
tropical grasslands.
• In conclusion, the tropical grassland is a home for elephants, giraffes, lions,
cheetahs, zebras, and other spectacular species.
• Tropical Grasslands are:
• East Africa- Savanna
• Brazil- Campos
• Venezuela- Llanos
Temperate Grasslands
• These grasslands are similar to tropical grasslands, except for the
climatic conditions.
• They have cold winters and warm summers with 25 cm and 75 cm.
of annual rainfall.
• Temperate grasslands have a mild range of temperatures, but they
have distinct seasons.
• They have hot summers and cold winters.
• During summers, the temperature can be well over 100 degrees
Fahrenheit.In the cold season, the temperature can reach up to 0
degrees Fahrenheit.
• Temperatures in this biome vary greatly between summer and
winter months.
• Shrublands are the best example of temperate grasslands.
• Moreover, these grasslands suffer extreme climates.
Desert ecosystem
Desert ecosystem

• Desert ecosystem is a biome or

geographical region characterized by
extremely arid conditions resulting in
a scarcity of water resources.
• It has an extremely dry area of land
with sparse vegetation.
• Characteristics of Desert Ecosystem:
• Unique Biodiversity: They are home
to a variety of specially adapted plant
and animal species that have evolved
to thrive in these challenging
conditions
• Precipitation: It is a region of scanty rainfall.
• They are formed in regions with about less than 25 cm of
annual rainfall.
• Coverage: Deserts cover about one-fifth of our planet.
• High Diurnal Range: Deserts are known for their high
temperatures during the day and cold temperature at night.
• Deserts are classified into two types – hot deserts and cold
deserts.
Adaptations of Desert Vegetation
• Extensive root system to tap underground water
• Xerophytic adaptation of plants: (e.g cactus, calotropis):
• Succulent and fleshy stem for storing water.
• Stems covered with waxy coating or hairs.
• Leaves are reduced to small scales and sometimes into
spikes/thorns to minimize transpiration.
• Waxy coatings on leaves and stems
• Phreatophytes’ deep root systems
enable them to reach the water
table during extended drought
periods, ensuring a consistent
water supply and eliminating the
need for water storage.
• Phreatophytes are signs of
groundwater that is drinkable.
 Adaptations of Desert Animals
• Nocturnal by habit to avoid the heat of
the sun.
• They can survive for months without
eating due to the fat they store in their
humps.
• Camel also known as “the ship of the
desert” can travel several days without
water (drink gallons of water at one go)
• To save water, excrete concentrated
urine.
• The body may adjust its temperature to
prevent perspiration and water loss.
Tundra Ecosystem

• Tundra ecosystems are treeless

regions found in the Arctic and on
the tops of mountains, where the
climate is cold and windy, and
rainfall is scant.
• These types of ecosystems are
mainly found in cold climates and
in those regions with limited or
scarce rainfall. Polar regions are
some examples of the tundra
ecosystem.
• Characteristics of Tundra Regions
• Low temperatures: The average temperature is -34 to -6 degrees
Celsius (-30 to 20 degrees Fahrenheit) in tundra region.
• Short growing seasons: The summer growing season is just 50 to 60
days, when the sun shines up to 24 hours a day.
• Permafrost: A layer of permanently frozen soil lies beneath the
surface, which can be a few inches to several feet thick.
• Minimal precipitation: Despite often being compared to deserts in
terms of moisture, the tundra receives low levels of precipitation,
often as snow.
• Limited biodiversity: The harsh conditions of the tundra result in
fewer plant and animal species compared to other biomes.
• Carbon sink: The tundra acts as a significant carbon storage area due
to slow decomposition rates in the cold environment.
The world has three types of tundra:
• Arctic Tundra which occurs north of the taiga belt in the far
Northern Hemisphere (It encompasses the land between the
North Pole and the boreal forest, including parts of Canada,
Russia, Greenland, Iceland, Norway, Sweden, and Finland.)
• Alpine tundra which prevails above the tree line in mountains
worldwide (in various mountain ranges such as the Rockies,
the Andes, the Himalayas, and the Alps).
• Antarctic tundra which includes several sub-Antarctic islands
and parts of the continent of Antarctica
Topic:-
Aquatic
Ecosystem

By:- Gourav Trivedi

• Habitat is a part of an ecosystem. The climate, plants, and
animals are the identities of a habitat. Ecosystems primarily
have two domains:
• Terrestrial or Land ecosystem
• Aquatic or Water ecosystem.
• Water supports many lives. Organisms which survive in water
are called aquatic organisms.
• They depend on water for their food, shelter, reproduction and
all other life activities.
Aquatic ecosystem
• An aquatic ecosystem includes a group of interacting
organisms which are dependent on one another and their
water environment for nutrients and shelter.
• Examples of aquatic ecosystem include oceans, lakes and
rivers.
• An aquatic ecosystem includes freshwater habitats like lakes,
ponds, rivers, oceans and streams, wetlands, swamp, etc. And
marine habitats include oceans, intertidal zone, reefs, seabed
and so on.
• The aquatic ecosystem is the habitat for water-dependent
living species including animals, plants, and microbes.
• Aquatic ecosystems are classified into two subgroups:
• 1) Freshwater ecosystems, such as rivers, lakes and ponds;
• 2) Marine ecosystems, such as oceans, estuary and mangroves.
• Aquatic ecosystems are classified on the basis of salinity into the
following types:
• Freshwater ecosystems: water on land which is continuously
cycling and has low salt content (always less than 5 ppt) is known
as fresh water.
• There are two types of freshwater ecosystems:
• 1) Static or still water (Lentic) ecosystems, e.g. Pond, lake, bogs
and swamps.
• 2) Running water (Lotic) ecosystems, e.g. Springs, mountain brooks,
streams and rivers.
• Marine ecosystems: the water
bodies containing salt
concentration equal to or above
that of seawater (i.e., 35 ppt or
above). E.g. Shallow seas and
open ocean.
• Brackish water ecosystems:
these water bodies have salt
content in between 5 to 35 ppt.
E.g. Estuaries, salt marshes,
mangrove swamps and forests.
 Aquatic
Organisms

• The aquatic organisms are classified on the

basis of their zone of occurrence.
• Neuston: These organisms live at the air-
water interface, e.g. floating plants.
• Periphyton: These are organisms which
remain attached to stems and leaves of
rooted plants or substances emerging
above the bottom mud such as sessile
algae.
• Plankton: Microscopic floating organisms
such as algae, diatoms, protozoans and larval
forms are called plankton.
• This group includes both microscopic plants
like algae (phytoplankton) and animals like
crustaceans and protozoans (zooplankton).
• The locomotory power of the planktons is
limited so that their distribution is controlled,
largely, by currents in the aquatic ecosystems.
• Nekton: This group contains powerful
swimmers that can overcome the water
currents.
• Benthos: The benthic organisms are those
found living at the bottom of the water mass.
Aquatic Ecosystems: Factors limiting
productivity of Aquatic Habitats

• Sunlight
• Sunlight penetration rapidly
diminishes as it passes down the
column of water. The depth to
which light penetrates lake
determines the extent of plant
distribution.
• Based on light penetration and
plant distribution they are
classified as photic and aphotic
zones
• Photic zone:
• Light penetrates Photosynthesis takes place.
• Photic (or “euphotic”) zone is the portion that extends from the lake
surface down to where the light level is 1% of that at the surface.
The depth of this zone depends on the transparency of water.
• Photosynthetic activity is confined to the photic zone.
• Both photosynthesis and respiration activity takes place.
• Aphotic zone
• The lower layers of the aquatic ecosystems, where light penetration
and plant growth are restricted forms the aphotic zone (profundal
zone). Only respiration activity takes place in this zone.
• The aphotic zone extends from the end of the photic zones to
bottom of the lake.
• Dissolved Oxygen
• Escapes water body through air-water interface & respiration
of organisms.
• Oxygen is less soluble in warm water. When dissolved oxygen
falls below 3-5 ppm, many organisms die.
• Transparency
• Transparency affects the extent of light penetration.
• Suspended particulate matters such as clay, silt,
phytoplankton, etc. Make the water turbid.
• Consequently it limits the extent of light penetration and the
photosynthetic activity in a significant way.
• Temperature
• Water temperatures are less subject to change, the aquatic
organisms have narrow temperature tolerance limits.
• As a result, even small changes in water temperature are a great
threat to the survival of aquatic organisms when compared to the
changes in air temperatures in the terrestrial organisms.
• Winterkill
• An ice layer on the top of a water body can effectively cut off light.
Photosynthesis stops but respiration continues in such water
body.
• If the water body is shallow, the oxygen gets depleted, and the
fish die. This condition is known as winterkill.
Dissolved Oxygen
• In freshwater the average concentration of dissolved oxygen is
10 parts per million by weight.
• This is 150 times lower than the concentration of oxygen in an
equivalent volume of air.
• Oxygen enters the aquatic ecosystem through the air-water
interface and by the photosynthetic activities of aquatic
plants.
• Dissolved oxygen escapes the water body through the air-
water interface and respiration of organisms (fish,
decomposers, zooplankton, etc.).
• The amount of dissolved oxygen retained in water is also
influenced by temperature.
• Oxygen is less soluble in warm water. Warm water also
enhances decomposer activity. Therefore, increasing the
temperature of a water body increases the rate at which
oxygen is depleted from the water.
• When the dissolved oxygen level falls below 3-5 ppm, many
aquatic organisms are likely to die.
 Biological Oxygen Demand (BOD)

• Water pollution by organic wastes is measured in

terms of Biochemical Oxygen Demand (BOD).
• BOD is the amount of dissolved oxygen needed by
bacteria in decomposing the organic wastes
present in water. It is expressed in milligrams of
oxygen per litre of water.
• The higher value of BOD indicates low DO content
of water.
• Since BOD is limited to biodegradable materials, it
is not a reliable method of measuring water
pollution.
Chemical oxygen demand (COD)
• Chemical oxygen demand (COD) is a slightly better mode used
to measure pollution load in water.
• It is the measure of oxygen equivalent of the requirement of
oxidation of total organic matter (i.e., biodegradable and non-
biodegradable) present in water.
Aquatic Ecosystems: Eutrophication
• Eutrophication is the process in which a water body becomes
overly enriched with nutrients, leading to the plentiful growth
of simple plant life.
• The excessive growth (or bloom) of algae and plankton in a
water body are indicators of this process.
• Eutrophication is considered to be a serious environmental
concern since it often results in the deterioration of water
quality and the depletion of dissolved oxygen in water bodies.
Eutrophic waters can eventually become “dead zones” that
are incapable of supporting life.
EUTROPHICATION
• Greek word – Eutrophia means adequate & healthy nu- trition.
• Eutrophication is a syndrome of ecosystem, response to the
addition of artificial or natural nutrients such as nitrates and
phosphates through fertilizer, sewage, etc that fertilize the
aquatic ecosystem.
• It is primarily caused by the leaching of phosphate and or
nitrate containing fertilisers from agricultural lands into lakes
or rivers.
• The growth of green algae which we see in the lake surface
layer is the physical identification of an Eu- trophication.
• Some algae and blue-green bacteria thrive on the excess ions
and a population explosion covers almost entire surface layer
is known as algal bloom. This growth is unsustainable,
however.
• As Algal Bloom covers the surface layer, it restricts the
penetration of sunlight. Diffusion of gas from atom
• Oxygen is required by all respiring animals in the water and it
is replenished by diffusion and photosynthesis of green plants.
• The oxygen level is already low because of the popula- tion
explosion and further oxygen is taken up by micro- organisms
which feed off the dead algae during decomposition process.
• Due to reduced oxygen level, fishes and other aquatic
organism suffocate and they die.
• The anaerobic conditions can promote growth of bac- teria
which produces toxins deadly to aquatic organ- isms, birds
and mammals.
• All this eventually leads to degradation of aquatic eco- system
and death of its organisms.
• It often leads to change in animal and plant population &
degradation of water & habitat quality.
HARMFUL ALGAL
BLOOMS

• Algae or phytoplankton are microscopic

organisms that can be found naturally in
coastal waters.
• They are major producers of oxygen and
food for many of the animals that live in
these waters.
• When environmental conditions are
favorable for their development, these
cells may multiply rapidly and form high
numbers of cells and this is called an
algal bloom.
• A bloom often results in a color
change in the water. Algal
blooms can be any color, but
the most common ones are red
or brown.
• These blooms are commonly
referred to as red or brown
tides.
• Most algal blooms are not
harmful but some produce
toxins and do affect fish, birds,
marine mammals and humans.
• The toxins may also make the
surrounding air difficult to
breathe. These are known as
Harmful Algal Blooms (HABs).
How are HABs dangerous to fish and
humans?
• HABS can deplete oxygen in water and lead to low dis- solved
oxygen levels.
• How it depletes oxygen? When masses of algae die and
decompose, the decaying process can deplete oxygen in the water,
causing the water to become so low in oxygen.
• When oxygen levels become too low, fish suffocate and die.
• Some algae species in blooms produce potent neurotox- ins that
can be transferred through the food web where they affect and even
kill the higher forms of life such as zooplankton, shellfish, fish,
birds, marine mammals, and even humans that feed either directly
or indirectly on them.
 LAKE ECOLOGY
• A lake is a body of water of considerable size, localized in a basin, that is
surrounded by land apart from a river or other outlet that serves to feed or
drain the lake.
• Lakes lie on land and are not part of the ocean, and therefore are distinct
from lagoons, and are also larger and deeper than ponds.
• Lake Ecosystem – Zones
• Lake ecosystem can be divided commonly into three zones.
• The first is the littoral zone which is the shallow zone close to the shore.
This is where the rooted wetland plants are noticed.
• The open water zone (or photic zone) and the deep water zone (or aphotic
zone) are the two zones that make up the offshore.
• Sunlight supports photosynthetic algae and the organisms that feed on
them in the open water zone.
• Because there is no sunshine in the
deep water zone, the food web relies on
detritus from the littoral and photic
zones.
• The lake’s overall production is the
consequence of plant growth in the
littoral zone mixed with plankton
growth in open water.
• This woody debris protects shorelines
from erosion while also providing
critical habitat for fish and nesting
birds.
 Ageing of Lakes
• Water bodies, like all living things, age with time.
• This ageing process is referred to as “eutrophication” in lakes.
• Algal bloom (excessive growth of planktonic algae) occurs when huge
levels of nutrients are present in water. Lakes age as a result of this.
• Lakes are formed as a result of diverse geological and geomorphic
events, and they ‘grow’ over time to change their morphological and
functional properties before eventually falling.
• Lakes derive their water from surface runoff (and sometimes
groundwater discharge), as well as various chemical compounds and
mineral matter eroded from the earth.
• Ageing occurs over millennia as the lakes gather mineral and organic
debris and gradually fill up.
CORAL REEFS
• Coral is actually a living animal.
• Corals are essentially animals, which are sessile,
meaning they permanently attach themselves to
the ocean floor.
• Coral has a symbiotic relationship (each gives
something to the other and gets something back
in return) with ‘zooxanthellae’ micro- scopic algae
which live on coral [i.e. Instead of living on the
sea floor, the algae lives up on the coral which is
closer to the ocean surface and so that the algae
gets adequate light].
• Note:- Corals share a symbiotic relationship with single-celled
algae called zooxanthellae
• Zooxanthellae assist the coral in nutrient
production through its photosynthetic activities.
• These activities provide the coral with fixed
carbon compounds for en- ergy, enhance
calcification, and mediate elemental nu- trient
flux.
• The tissues of corals themselves are actually not
the beautiful colors of the coral reef, but are
instead clear (white). The corals receive their
coloration from the zooxanthellae living within
their tissues.
• The host coral polyp in return provides its zooxanthellae with a
protected environment to live within, and a steady supply of
carbon dioxide for its photosynthetic processes.
• There are two types of corals: hard corals and soft cor- als,
such as sea fans and gorgonians. Only hard corals build reefs.
• The builders of coral reefs are tiny animals called polyps.
• As these polyps thrive, grow, then die, they leave their
limestone (calcium carbonate) skeletons behind.
• The limestone is colonized by new polyps. Therefore, a coral
reef is built up of layers of these skeletons covered ultimately
by living polyps.
• Coral reefs are the colonies of tiny living creatures that are
found in oceans. They are the underwater structures that are
formed of coral polyps that are held together by calcium
carbonate.
• Coral reefs are also regarded as the tropical rainforest of the
sea and occupy just 0.1% of the ocean’s surface but are home
to 25% of marine species.
• They are usually found in shallow areas at a depth less than
150 feet. However, some coral reefs extend even deeper, up to
about 450 feet.
• Coral polyps are individual corals that are found on the
calcium carbonate exoskeletons of their ancestors.
• Corals can be found in all the oceans but the biggest coral
reefs are mostly found in the clear, shallow waters of the
tropics and subtropics.
• The largest of these coral reef systems, The Great Barrier Reef
in Australia, the largest coral reef is more than 1,500 miles
long.
Growth Conditions for Coral Reefs
• The temperature of the water should not be below 20°C. The
most favourable temperature for the growth of the coral reefs
is between 23°C to 25°C. The temperature should not exceed
35°C.
• Corals can survive only under saline conditions with an
average salinity between 27% to 40%.
• Coral reefs grow better in shallow water having a depth less
than 50 m. The depth of the water should not exceed 200m.
Factors Affecting Coral Reefs
• Extreme climate conditions: High temperature of water leads
to the declination of these corals as they cannot survive in
high temperature. As estimated by scientists, most of the coral
reefs of the world will soon decline with the increasing rates of
ocean warming.
• Overfishing: It is another major concern as it is leading to an
ecological imbalance of the coral reefs.
• Coastal development: Development of coastal infrastructure
and tourist resorts on or close by these coral reefs causes
significant damages.
• Pollution: The toxic pollutants which are dumped directly into
the ocean can lead to the poisoning of the coral reefs as it
increases the nitrogen level of the seawater leading to an
overgrowth of algae.
• Sedimentation: Construction along the coasts and islands
lead to soil erosion increasing the sediments in the river. As a
result, it can smother corals by depriving them of the light
needed to survive.
Types of Coral Reefs
• Coral Reefs are differentiated into three categories based on
their shape, nature and mode of occurrence.
• 1. Fringing Reef:
• 2. Barrier Reef:
• 3. Atolls:
Fringing Reef:
• The coral reefs that are found very close to the land and forms
a shallow lagoon known as Boat Channel are called Fringing
Coral Reefs.
• The Fringing Reefs develop along the islands and the
continental margins.
• They grow from the deep bottom of the sea and have their
seaward side sloping steeply into the deep sea.
• Fringing Reefs are the most commonly found coral reefs
among the three.
Barrier Reef:
• Barrier Reefs are considered as the largest, highest and widest
reefs among the three coral reefs.
• They develop off the coast and parallel to the shore as a
broken and irregular ring.
• Being the largest reef among the all, they run for 100kms and is
several kilometres wide.
• One example of Barrier Reef is the Great Barrier Reef of
Australia which is 1200 mile long.
Atolls

• An atoll can be defined as a reef that

is roughly circular and surrounds a
large central lagoon.
• This lagoon is mostly deep having a
depth of 80-150 metres.
• The atolls are situated away from the
deep sea platforms and are found
around an island or on a submarine
platform in an elliptical form.
• For example Fiji Atolls, Suvadivo in
Maldives and Funafoothis Atoll of
Ellice.
Importance of Coral Reefs
• Coral Reefs play an important role in the following ways.
• They protect coastlines from the damaging effects of wave
action and tropical storms.
• They provide habitats and shelter for many marine organisms.
• They are the source of nitrogen and other essential nutrients
for marine food chains.
• They assist in carbon and nitrogen-fixing.
• They help with nutrient recycling.
• The study of coral reefs is essential for scientifically testable
records of climatic events over the past million years.
• The fishing industry depends also on coral reefs.
• Coral reefs are also key indicators of global ecosystem health.
Coral Reefs in India
• India has its coastline extending over 7500 kilometres. It is due
to the subtropical climatic conditions, there are a very few
coral reefs in India.
• The major coral reefs in India includes the Palk Bay, the Gulf of
Mannar, the Gulf of Kutch, the Andaman and Nicobar Islands
and Lakshadweep Islands.
• Among all these coral reefs, the Lakshadweep reef is an
example of atoll while the rest are all fringing reefs.
What is Coral
Bleaching?
• The coral and the zooxanthellae share a symbiotic
relationship and 90% of the nutrients that are
produced by the algae are transferred to the coral
hosts.
• But this relationship gets affected under severe
environmental stress which causes the loss of
symbiotic algae (zooxanthellae).
• As a result, the white calcium-carbonate
exoskeleton is visible through its transparent
tissue leading to a condition known as Coral
Bleaching.
• The corals become vulnerable in the absence of
the algae and begin to die if the temperature of the
sea remains high for weeks.
• Coral polyps are short-lived microscopic
organisms that live in colonies. They
flourish in shallow, mud-free and warm
waters.
• Coral reefs are the colonies of tiny living
creatures that are found in oceans.
• Coral are bright and colourful because of
microscopic algae called zooxanthellae.
• The zooxanthellae live within the coral in
a mutually beneficial relationship, each
helping the other survive.
• The coral and the zooxanthellae share a symbiotic
relationship. 90% of the nutrients that are produced by the
algae are transferred to the coral hosts.
• But when the ocean environment changes, for instance, if it
gets too hot, the coral stresses out and expels the algae.
• As the algae leaves, the coral fades until it looks like it’s been
bleached.
• If the temperature stays high, the coral won’t let the algae
back, and the coral will die.
 Causes of Coral Bleaching
• Extreme climate conditions: High temperature of water leads to the
declination of these corals as they cannot survive in high
temperatures. As estimated by scientists, most of the coral reefs of
the world will soon decline with the increasing rates of ocean
warming.
• Ocean Acidification: Oceans absorb more carbon dioxide due to a
rise in CO2 levels. This increases the acidity of ocean water. This
inhibits the corals’ ability to create calcareous skeletons that
essential for their survival.
• Pollution: The toxic pollutants which are dumped directly into the
ocean can lead to the poisoning of the coral reefs as it increases the
nitrogen level of the seawater, leading to an overgrowth of algae.
• Sedimentation: Construction along the coasts and islands
lead to soil erosion, increasing the sediments in the river. As a
result, it can smother corals by depriving them of the light
needed to survive.
• Infectious Diseases: Vibrio shiloi is a bacterium that inhibits
the photosynthesis of zooxanthellae. This bacterium becomes
more potent with an increase in sea temperatures.
• Coastal development: Development of coastal infrastructure
and tourist resorts on or close by these coral reefs causes
significant damages.
• Human activities: Over-fishing, coral mining, development of
industrial areas near coral ecosystems etc. Impact coral
ecosystem.
 Mangrove Forests

• Mangrove Forests consist of special trees

that grow in salty or brackish water along
coastlines and tidal rivers, mainly in warm
equatorial climates.
• They are found worldwide in tropical and
subtropical regions, with the largest areas
near the equator.
• The International Day for the
Conservation of the Mangrove Ecosystem
is celebrated annually on the 26th of July.
Unique Characteristics
of Mangrove Forests
• There are about 110 types of mangrove
species, but only 54 of them are considered
“true Mangrove Forests,” mainly found in
mangrove habitats.
• High Salt Tolerant: These salt-tolerant trees
are well adapted to live in harsh coastal
environments with their complex filtration and
root systems.
• They form distinct habitats known as the
mangrove biome, which protects them from
strong waves and sediment collection.
• Unique adaptation: Different mangrove
species have evolved various adaptations to
cope with their unique environments. For
example, the red mangrove stays above
water by using stilt or prop roots and
absorbs air through lenticels in its bark.
• The black mangrove, on the other hand,
develops specialized root-like structures
called pneumatophores that emerge out of
the ground like straws to breathe and thrives
on higher ground. These roots also help with
nutrient transport within the plants.
• Direct Absorption of Gases: Since the soil is consistently
waterlogged, there is little free oxygen available, making it less
nutritious. To compensate, they absorb gases directly from the
atmosphere using pneumatophores.
• Limit salt intake: Red mangrove have impermeable roots that
prevent salt from entering the rest of the plant. They store the
excluded salt in the root cortex.
• Conserve Water: They control the opening of their leaf pores
and adjust their leaf orientation to avoid losing too much water.
For example, red mangroves need regular misting with fresh
water to survive when grown in captivity.
• Seed dispersal system: The seeds are buoyant,
helping them disperse through water.
• Some mangroves produce seeds that germinate
while still attached to the parent tree.
• The germinated seedlings can grow within the
fruit or extend out to form propagules, which are
ready-to-go seedlings.
• These propagules can float in water for long
distances and remain dormant until they find a
suitable environment to root and grow into new
mangrove trees.
• Pneumatophores, commonly found in mangrove
species that grow in saline mud flats, are lateral
roots that grow upward out of the mud and water to
function as the site of oxygen intake for the
submerged primary root system.
• Buttress roots also known as plank roots/ stilt roots
are large, wide roots on all sides of a shallowly
rooted tree. Typically, they are found in nutrient-
poor tropical forest soils that may not be very deep.
They prevent the tree from falling over (hence the
name buttress) while also gathering more nutrients.
• Limiting water loss: They can restrict the opening of their
stomata (pores on the leaf surfaces, which exchange carbon
dioxide gas and water vapor during photosynthesis).
• Increasing survival of offspring: Mangrove seeds are buoyant
and are therefore suited to water dispersal.
• Adaptations to low oxygen: By propping themselves above the
water level with stilt roots and can then absorb air through
pores in their bark (lenticels).
• Nutrient uptake: Pneumatophores (aerial roots) allow
mangroves to absorb gases directly from the atmosphere.
• Limiting salt intake: Mangroves exclude salt by having
significantly impermeable roots.
Global distribution of Mangroves
• According to Global Forest Resource Assessment, 113
countries have Mangrove forests covering estimated 14.79
million hectares.
• The largest Mangrove area is in Asia (5.55 million hectares),
followed by Africa (3.24 million hectares), North and Central
America (2.57 million hectares) and South America (2.13
million hectares) and Oceania (1.30 million hectares).
• Country wise: About 40% of global mangrove cover is in just
four countries: Indonesia > Brazil > Nigeria > Mexico.
Distribution of
Mangroves in India
• According to India State of Forest
Report, Mangrove cover in India is
4,992 sq. Km constituting 0.15% of
total area of India.
• State-wise Mangrove Cover: West
Bengal > Gujarat > Andaman &
Nicobar Islands > Andhra Pradesh
> Maharashtra > Odisha > Tamil
Nadu > Goa > Karnataka > Kerala >
Daman & Diu & Dadra & Nagar
Haveli > Puducherry.
Sundarbans
• Located within the largest mangrove forest in the world.
Located in the delta of Rivers Ganges and Brahmaputra on the
Bay of Bengal in India & Bangladesh.
• Sundarbans Tiger Reserve is situated within the Site and part
of it has been declared a “critical tiger habitat” under national
law and also a “Tiger Conservation Landscape” of global
importance.
• The Site is also home to a large number of rare and globally
threatened species such as the critically endangered northern
river terrapin (Batagurbaska), the endangered Irrawaddy
dolphin, and the vulnerable fishing cat .
• It is listed as World Heritage Site and also in UNESCO
Biosphere Reserve.
Importance of Mangroves
• Important refuges of coastal biodiversity: Mangroves provide
breeding grounds for marine biodiversity.
• Under water the root system provides nesting and feeding
grounds for juvenile fish, oysters, mussels, and sharks. Above
ground mangroves provide homes for cranes, eagles and
monkeys.
• Broad and towering canopies provide nesting and resting
ground for migratory and sea birds and other wildlife.
• Act as bio-shields: Mangroves acts as natural barriers against
rising tides and storm-surges.
• Mangrove ecosystems prevent property damages and reduce
flood risk in coastal areas.
• The dense root systems help stabilize shorelines by trapping
sediments and reducing the impact of waves and tides.
• They are an effective check against Cyclones and Tsunamis in
the coastal regions.
• Source of wide variety of biomass and forest products:
Communities along the coast depend on mangrove wood for
fuel, construction, fish traps and boat building and non-wood
products such as traditional medicine.
• Acts carbon sinks: Mangroves capture carbon from
atmosphere for growth. It is believed that mangroves hold up
to four times the amount of carbon as compared to forested
ecosystems like temperate and boreal forests.
• Improve water quality: Mangroves act as natural water filter,
trapping sediments and pollutants from runoff before they
reach open sea. Thus, improving water quality.
• Tourism and recreation: Mangroves have high aesthetic value
and are important sites for ecotourism, bird-watching and
other recreation activities.
Challenges to Mangroves
1. Increasing human population in coastal areas and rising
demand for land, timber, fodder, fuel-wood and other non-
wood forest products.
2. Growing land reclamation for agriculture and
industrialization
3. Discharge of untreated domestic sewage and industrial
effluents
4. Damming of rivers which curbs the flow of sediments to
coastal areas. The silt flow is essential for regeneration and
growth of mangroves.
Steps to promote mangrove forests.
1. Natural regeneration
2. Promotion of plantation activities in suitable land on the banks of
rivers near estuary and on inter-tidal mudflats associated with
the areas that are inundated by sea water on a daily cycle.
3. Regeneration of Mangrove forests in areas where it has been
degraded.
4. Sharing of best practices.
5. Conservation of existing mangroves.
6. Notification of protected areas in mangroves.
7. Ensuring ecological flows in rivers.
8. Effective implementation of Coastal Regulation Zone Guidelines.
 Wetland Ecosystem
• Wetlands are areas of marsh or peatland with water that is static or
flowing, fresh, brackish or saline, including areas of marine water the
depth of which at low tide does not exceed 6 m.
• Areas of marsh, fen, peatland/water, whether natural (or) artificial,
permanent (or) temporary with water that is static (or) flowing, fresh,
brackish (or) salt, including areas of marine water the depth of which at
low tide does not exceed 6 meters.
• Wetlands are areas where water is the primary factor controlling the
environment and the associated plant and animal life. They occur
where the water table is at or near the surface of the land, or where the
land is covered by water.
• Wetlands are transition zones (ecotone) between terrestrial and
aquatic ecosystems.
• These habitats experience periodic flooding from adjacent
deepwater habitats and therefore supports plants and animals
specifically adapted to such shallow flooding or waterlogging.
• Waterlogged soil adapted plant life (hydrophytes), and hydric
soils (not enough O2) are the chief characteristics of wetlands.
• India has over 27,000 wetlands, of which 23,000+ are inland
wetlands, and around 4000 are coastal wetlands.
• Wetlands occupy 18.4% of the country’s area of which 70% are
under paddy cultivation.
 Types of Wetlands
• Coastal Wetlands: Coastal wetlands are
found in the areas between land and open
sea that are not influenced by rivers such as
shorelines, beaches, mangroves and coral
reefs.
• A good example is the mangrove swamps
found in sheltered tropical coastal areas.
• Shallow lakes and ponds: These wetlands
are areas of permanent or semi-permanent
water with little flow. They include vernal
ponds, spring pools, salt lakes and volcanic
crater lakes.
• Marshes: These are periodically
saturated, flooded, or ponded with
water and characterized by
herbaceous (non-woody) vegetation
adapted to wet soil conditions.
Marshes are further characterized as
tidal marshes and non-tidal marshes.
• Swamps: These are fed primarily by
surface water inputs and are
dominated by trees and shrubs.
Swamps occur in either freshwater or
saltwater floodplains.
• Bogs: Bogs are waterlogged
peatlands in old lake basins or
depressions in the landscape.
Almost all water in bogs comes
from rainfall.
• Estuaries: The area where rivers
meet the sea and water changes
from fresh to salt can offer an
extremely rich mix of
biodiversity. These wetlands
include deltas, tidal mudflats
and salt marshes.
What is the Importance of Wetlands?
• Biodiversity: Wetlands are home to a diverse array of plant and
animal species, many of which are endangered or threatened.
• Climate regulation: Wetlands play an important role in
regulating the Earth’s climate by storing carbon and regulating
water cycles.
• Water management: Wetlands help to regulate water quality
and quantity, reducing the risk of flooding and ensuring a
reliable supply of clean water.
• Recreation: Wetlands are popular destinations for outdoor
recreation, including birdwatching, fishing, and hiking.
• Wetlands are habitat to aquatic flora and fauna, numerous
species of native and migratory birds.
• Wetlands are an important resource for sustainable tourism.
• They carry out water purification, filtration of sediments and
nutrients from surface water.
• They help in nutrients recycling, groundwater recharging and
stabilisation of local climate.
• Play an important role in flood mitigation by controlling the
rate of runoff.
• Buffer (act as a riparian buffer) shorelines against erosion and
pollutants.
• They act as a genetic reservoir for various species of plants
(especially rice).
Reasons for depletion(Threats)
• Habitat destruction: Wetlands are often drained or filled in for
agriculture, urban development, or transportation infrastructure.
• Pollution: Wetlands are vulnerable to pollution from agricultural
runoff, industrial discharge, and urban runoff.
• Climate change: Changes in temperature and precipitation patterns
can alter the hydrology and plant communities of wetlands, making
them more vulnerable to degradation and loss.
• Invasive species: Non-native plant and animal species can
outcompete native species and alter the ecology of wetland
ecosystems.
Ramsar Convention
• It is an international treaty for “the conservation and sustainable
use of wetlands”.
• It is also known as the Convention on Wetlands.
• It is named after the city of Ramsar in Iran.
• The Convention was signed on 2nd of February 1971.
• The 2nd of February each year is World Wetlands Day.
• Number of parties to the convention (COP) is 171.
• At the centre of the Ramsar philosophy is the “wise use” of
wetlands.
• Wise use: maintenance of ecological character within the context
of sustainable development.
• The Ramsar Convention came into
force in 1975 with a mission to conserve
and use wisely all wetlands through
local and national actions and
international cooperation, as a
contribution towards achieving
sustainable development throughout
the world.
• As of January 2024, there are 172
contracting parties to the Ramsar
Convention.
Ramsar Site
• At the time of joining the Convention, each Contracting Party
undertakes to designate at least one wetland site for inclusion in
the List of Wetlands of International Importance.
• The inclusion of a “Ramsar Site” in the List embodies the
government’s commitment to take the steps necessary to ensure
that its ecological character is maintained.
• There are over 2,300 Ramsar Sites on the territories of 172 Ramsar
Contracting Parties across the world.
• The countries with the most Sites are the United Kingdom with 175
and Mexico with 142.
• Bolivia has the largest area under Ramsar protection.
The Montreux Record
• The Montreux Record is a register of wetland sites on the List of
Wetlands of International Importance where changes in ecological
character have occurred, are occurring, or are likely to occur as a
result of technological developments, pollution or other human
interference.
• It is maintained as part of the Ramsar List.
• At present, two wetlands of India are in Montreux Record:
• Keoladeo National Park (Rajasthan) and
• Loktak Lake (Manipur).
• Note: Chilka Lake (Odisha) was placed in the record but was later
removed from it.
Ramsar Sites in India
• As of 2024, India has 85 Ramsar Sites, the highest number in
South Asia. It encompasses diverse ecosystems including
freshwater lakes, marshes, mangroves, and high-altitude
lakes.
• These sites play a critical role in supporting biodiversity,
providing habitat for many species of flora and fauna.
• This development places India on the third rank globally in
terms of the number of Ramsar sites, equaling China’s count.
The UK currently leads with 175 sites, followed by Mexico with
144.
• June 2024: India marked World Environment Day by
designating Nagi Bird Sanctuary and Nakti Bird Sanctuary as
its newest Wetlands of International Importance.
• These “Ramsar Sites” are both man-made reservoirs situated
in the Jhajha forest range of Jamui District in Bihar, India.
• These additions take the total tally to 82 in India.
• August 2024: India has added three more Ramsar sites to the
network, taking the tally to 85.
• Nanjarayan Bird Sanctuary and Kazhuveli Bird Sanctuary in
Tamil Nadu and Tawa Reservoir of Madhya Pradesh have been
added to India’s Ramsar sites list.
• In January 2024, five new sites
were added to the list of Ramsar
Sites in India.
• Ankasamudra Bird Conservation
Reserve – Karnataka
• Aghanashini Estuary – Karnataka
• Magadi Kere Conservation
Reserve – Karnataka
• Karaivetti Bird Sanctuary – Tamil
Nadu
• Longwood Shola Reserve Forest –
Tamil Nadu
• Sundarbans is the largest Ramsar
Site of India.
• Chilika Lake (Orissa) and Keoladeo
National Park (Rajasthan) were
recognized as the first Ramsar
Sites of India.
• Renuka Wetland (Area – 20 ha) in
Himachal Pradesh is the smallest
wetland of India.
• World’s First Ramsar site was
identified in 1974, which was the
Cobourg Peninsula in Australia.